Mast Therapeutics Announces New Data Supporting MST-188 In Sickle Cell Disease

SAN DIEGO, April 14, 2014 /PRNewswire/ -- Mast Therapeutics, Inc. (NYSE MKT: MSTX) today announced that, in an ex vivo study conducted at Loyola University Medical Center, MST-188 reduced the mean erythrocyte sedimentation rate (ESR) by 50% relative to control in blood collected from individuals with sickle cell disease. ESR, a common laboratory test and measure of inflammation, describes the rate at which red blood cells (RBC) travel through anti-coagulated blood. When an inflammatory process is present, the high proportion of proteins in the blood, such as fibrinogen, cause RBC to form aggregates, increasing viscosity and impairing microvascular blood flow. Data from the study were presented at the 8^th Annual Sickle Cell Disease Research & Educational Symposium, currently underway in Miami.

Martin Emanuele, Ph.D., Senior Vice President, Development, said: "Patients suffering vaso-occlusive crisis experience an inflammatory state where cells, proteins, and other molecules increasingly adhere to each other and blood vessel walls, resulting in physical 'log jams' that obstruct blood flow, cause severe pain, and accelerate organ damage and failure. Reducing RBC aggregation may be integral to restoring normal blood flow to tissue. The data from this study are consistent with observations in prior studies that MST-188 decreases blood viscosity and RBC aggregation and improves microvascular blood flow, and supportive of the potential for MST-188 to shorten the duration of sickle cell crisis."

Dr. Emanuele continued: "It is widely understood that multiple biological processes contribute to vaso-occlusion and that an effective solution requires a broad, multi-modal approach rather than a single targeted therapy. In addition to the effects on RBC aggregation, our data suggest that MST-188 addresses cell adhesion and platelet activation, reduces hemolysis, lowers blood viscosity and limits reperfusion injury following restoration of blood flow. We plan to conduct additional studies that will augment the growing body of data supporting the broad utility of MST-188 as a multi-modal approach to treating sickle cell disease."

Abstract Information:

The abstract entitled "Effect of Purified Poloxamer 188 or Various Dextrans on Erythrocyte Sedimentation Rate in Patients with Sickle Cell Disease" was presented by Martin Emanuele, Ph.D., Senior Vice President, Development
The abstract is available on the Company's website at www.masttherapeutics.com/technology/publications/.

About Mast Therapeutics

Mast Therapeutics, Inc. is a publicly traded biopharmaceutical company headquartered in San Diego, California. The Company is leveraging the MAST (Molecular Adhesion and Sealant Technology) platform, derived from over two decades of clinical, nonclinical and manufacturing experience with purified and non-purified poloxamers, to develop MST-188, its lead product candidate, for serious or life-threatening diseases and conditions typically characterized by impaired microvascular blood flow and damaged cell membranes.

The Company is enrolling subjects in EPIC, a pivotal phase 3 study of MST-188 in sickle cell disease, and has initiated a phase 2, clinical proof-of-concept study to evaluate whether MST-188 improves the effectiveness of recombinant tissue plasminogen activator therapy in patients with acute limb ischemia. The Company also is developing MST-188 in heart failure and plans to announce its clinical development plans in this indication in the second half of 2014. More information can be found on the Company's web site at www.masttherapeutics.com. (Twitter: @MastThera)

Mast Therapeutics™ and the corporate logo are trademarks of Mast Therapeutics, Inc.

Forward Looking Statements

Mast Therapeutics cautions you that statements included in this press release that are not a description of historical facts are forward-looking statements that are based on the Company's current expectations and assumptions. Such forward-looking statements include, but are not limited to, statements relating to the potential of MST-188 in sickle cell disease, including with respect to shortening the duration of vaso-occlusive crisis, and the Company's clinical development plans for MST-188 in sickle cell disease and heart failure. Among the factors that could cause or contribute to material differences between the Company's actual results and the expectations indicated by the forward-looking statements are risks and uncertainties that include, but are not limited to: the uncertainty of outcomes in ongoing and future studies of the Company's product candidates and the risk that its product candidates, including MST-188, may not demonstrate adequate safety, efficacy or tolerability in one or more such studies, including EPIC; delays in the commencement or completion of clinical studies, including as a result of difficulties in obtaining regulatory agency agreement on clinical development plans or clinical study design, opening trial sites, enrolling study subjects, manufacturing sufficient quantities of clinical trial material, being subject to a "clinical hold," and/or suspension or termination of a clinical study, including due to patient safety concerns or lack of funding; the potential for institutional review boards or the FDA or other regulatory agencies to require additional nonclinical or clinical studies prior to initiation of a phase 2 clinical study of MST-188 in heart failure or other indications; the risk that, even if clinical studies are successful, the FDA or other regulatory agencies may determine they are not sufficient to support a new drug application; the potential that, even if clinical studies of a product candidate in one indication are successful, clinical studies in another indication may not be successful; the Company's reliance on contract research organizations (CROs), contract manufacturing organizations (CMOs), and other third parties to assist in the conduct of important aspects of development of its product candidates, including clinical studies, and regulatory activities for its product candidates and that such third parties may fail to perform as expected; the Company's ability to obtain additional funding on a timely basis or on acceptable terms, or at all; the potential for the Company to delay, reduce or discontinue current and/or planned development activities, including clinical studies, partner its product candidates at inopportune times or pursue less expensive but higher-risk and/or lower return development paths if it is unable to raise sufficient additional capital as needed; the risk that, even if the Company successfully develops a product candidate in one or more indications, it may not realize commercial success with its products and may never generate revenue sufficient to achieve profitability; the risk that the Company is not able to adequately protect its intellectual property rights relating to the MAST platform and MST-188 or AIR001 and prevent competitors from duplicating or developing equivalent versions of its product candidates; and other risks and uncertainties more fully described in the Company's press releases and periodic filings with the Securities and Exchange Commission. The Company's public filings with the Securities and Exchange Commission are available at www.sec.gov.

You are cautioned not to place undue reliance on forward-looking statements, which speak only as of the date when made. Mast Therapeutics does not intend to revise or update any forward-looking statement set forth in this press release to reflect events or circumstances arising after the date hereof, except as may be required by law.